Add hierarchy to the CSV export and allow import of exported CSV

Problem/Motivation

Taxonomy manager is a super helpful tool to export and import taxonomy terms including their structure and order across Drupal installations easily.

Sadly, the simple process lacks the ability to export and import

• additional (scalar) fields
• taxonomy term descriptions

I think exporting entity references and files should be out of scope due to its complexity.

Several issues from the past show the need. I created this new feature request, nonetheless, because I think they all don't go into the right direction.

The module already offers a CSV export (which allows fields) but no import of the exported CSV.

Steps to reproduce

Try exporting and importing a taxonomy structure including

• order
• hierarchy
• scalar field values

using Taxonomy Manager.

• CSV export allows fields, but lacks hierarchy
• There's no CSV import for the export

Proposed resolution

a) Solve hierarchy export in CSV e.g. through indentation, prefix or parent term name (risky)

b) Allow importing the exported CSV:
Either this could be done in taxonomy_manager itself OR we could link the best contrib module available for that, which allows importing the prepared CSV.

Here are possible modules to check for that before implementing our own solution:

• https://www.drupal.org/project/migrate_source_csv
• https://www.drupal.org/project/taxonomy_import
• https://www.drupal.org/project/taxonomy_csv
• https://www.drupal.org/project/etm (I asked for this feature over there now: #3624953: Allow importing fields on terms
• https://www.drupal.org/project/terms_export_import
• https://www.drupal.org/project/taxonomy_overview

Remaining tasks

1. Discuss
2. Implement
3. Test
4. Release

User interface changes

API changes

Data model changes